Nano-encapsulated solvent via pickering emulsion in NaOH aqueous solution for indoor CO2 capture

Abstract Considering the limitations of indoor ventilation owing to air pollution, CO2 concentration rises rapidly to 3000 ppm, which is a level that can affect human health. It is essential to develop materials to reduce naturally occurring CO2 in the buildings. Herein, a nano-encapsulated solvent (NES) via Pickering emulsion is proposed for indoor CO2 capture. NaOH aqueous solution is wrapped with hydrophobic surface-functionalized SiO2 (HS-SiO2) nanoparticles, and the corrosiveness of NaOH is not caused by HS-SiO2 wall. CO2 capture capacity of NES-NaOH is evaluated as 7.57 mmol-CO2/g-solvent which is the highest compared to other solvents including metal-organic frameworks (MOFs); it exhibits excellent structural stability in terms of temperature, time, moisture, and CO2 reaction. NES-NaOH presents high selectivity toward CO2 molecules due to the characteristics of NaOH with high gas permeability of macroporous silica wall and it is dispersed in a silicone oil harmless to human body. It is concluded that NES-NaOH can be successfully applied to air purifier filter to control the CO2 concentration in buildings.